1. Field of the Invention
The present invention relates to the formation of a stable colloidal dispersion of fine particles. More particularly, the invention relates to the formation of nanocomposites.
More specifically, the invention relates to the formation of continuous films of submicron particles.
2. Description of the Prior Art
Prior art formation of submicron or nanometer structures have predominantly included the formation of large particles which are subsequently ground or milled until particles of the desired size are achieved. The grinding and milling times associated with the formation of such particles ranged from 120 to 2900 hours.
A method of forming dry magnetic submicron particles by precipitation of a magnetic oxide in an ion exchange resin is discussed and exemplified by Ziolo in U.S. Pat. No. 4,474,866. According to the method employed, an ion exchange resin is loaded with a magnetic ion. The resin is then recovered and dried. The magnetic polymer resin is then micronized to form a fine magnetic powder. The dry magnetic particles formed according to Ziolo, U.S. Pat. No. 4,474,866, like other typical prior art materials, could not be directly suspended in an aqueous medium to form a stable colloid.
Difficulties have been encountered in forming and maintaining nanoscale materials due to the tendency of the particles to aggregate to reduce the energy associated with the high area to volume ratio. This aggregation leads to additional difficulties in the preparation of homogeneous dispersions and thin continuous films produced therefrom.
Prior art formation of films of submicron particles have required the spreading of fine particles which resulted in uneven and noncontinuous films. In addition, if the particles were dispersed in a fluid medium, upon evaporation of the fluid medium, film properties were not continous but were individual islands of particulate material. By contrast, the fluids of the present material are a composite of a crushed matrix material and nanometer particles in an aqueous vehicle. Upon evaporation of the aqueous vehicle in the present invention, the particles are left in a continuous film joined by a network of this crushed resin material.